TAMARAC (CBSMiami) – Broward Sheriff’s investigators are trying to piece together what triggered a violent rampage on New Year’s Day that left two people dead and one man with life-threatening injuries.

Investigators said 56-year-old Clive Muir first shot and killed 21-year-old Anne Nau at her apartment in Tamarac just after noon.

Nau was an assistant manager at a nearby Boston Market restaurant where Muir had been fired as manager recently.

Muir then drove to the restaurant on University Drive and shot 33-year old Jason Claire, the new manager for about two months.

“The people in the restaurant noticed him approaching and an employee tried to lock the office door,” said Gina Carter, a B.S.O. spokeswoman. “Unfortunately she was unable to do so and he gained entry. Once inside he shot a second victim.”

Muir’s friend, Bobby Sinclair, told CBS4 that Muir had recently left his gun with him, which Sinclair had regrettably returned. He believed Muir may have been in love with Nau and was upset over losing his job working with her.

“I think she wasn’t interested in him anymore,” said Sinclair. “But he was in love with her so much it was very hard for him to get over it. I feel guilty. If I had kept it this might not have happened.”

“She was on the road to somewhere,” said Kay Fragelus, a friend of Anne Nau’s.

Fragelus said the young introvert was a hard worker who was putting herself through college.

“I think she’s studying to become a cardiologist,” Fragelus explained. “So to be that young, living on your own, paying your own bills and you’re a manager at 21, that’s something great.”